The invention relates to a linear drive for a belt pretensioner in a vehicle safety belt system comprising a cylinder in which a piston is slidably accommodated, a pyrotechnical gas generator with an impact fuse, and a vehicle-sensitive sensor inertial body slidably arranged in a housing secured to the vehicle body.
In a linear drive of this type, an impact member, or striker, is held in a rest position by locking means spaced away from the impact fuse of the gas generator and is spring-loaded in the direction against the impact fuse. By vehicle-sensitive movement of the sensor inertial body the striker is released, the gas generator is thus activated and the piston is driven by the compressed gases liberated from the gas generator movement of the piston being transmitted to some component in the safety belt system to remove slack of the belt.
This type of linear drive can be arranged separate from a belt retractor or a fitting of the safety belt system, since the piston may be connected by a cable to the belt retractor or fitting. Using a cable also makes it possible to provide a deflection thus creating a high freedom of choice of location for accommodating the linear drive in the vehicle relative to the other components of the safety belt system.